1. Field of the Invention
The present invention relates to an LED testing apparatus and a method thereof that can be applied to backlights or lighting devices, and more particularly, to an LED testing apparatus and a method thereof that can ensure the reliability of LED tests by automatically performing a test to determine whether an LED is acceptable or defective, using visible rays or ultraviolet rays.
2. Description of the Related Art
In general, light emitting diodes (LEDs) refer to semiconductor devices that emit light of various colors by configuring light sources by altering the compound semiconductor material, such as GaAs, AlGaAs, GaN or InGaInP.
High-brightness, high-quality LED products rather than general-purpose, low-brightness LED products can be manufactured in line with the rapid progress in semiconductor technology. Furthermore, thanks to the realization of blue and white LEDs having excellent properties, the application range of these LEDs has been expanded to next-generation light sources and displays. Among these various LEDS, white LEDs will now be described with reference to FIG. 1.
FIG. 1 is a cross-sectional view illustrating the configuration of a white LED according to the related art.
In a white LED, shown in FIG. 1, according to the related art, lead frames 20, consisting of first and second lead frames 21 and 22, are formed on the inner bottom of a bucket 10 that may be formed of a synthetic plastic resin. A blue LED 30 is mounted and connected to the first lead frame 21, while a diode 40 is mounted and connected to the second lead frame 22. The blue LED 30 and the diode 40 are electrically connected to each other through a bonding wire 50.
Here, in order to emit white light using a blue LED and a yellow phosphor, a blue LED chip package is filled with an encapsulant 60, formed of silicone resin mixed with a yellow phosphor. That is, the inside of the bucket 10 is coated with the encapsulant 60, which contains the yellow phosphor, so that blue light, emitted from the blue LED 30, changes into white light by the yellow phosphor in the encapsulant 60.
Recently, in order to complement green and red light-emitting areas, a green or blue phosphor as well as the yellow phosphor may be added to the encapsulant 60.
In the process of manufacturing the white LED according to the related art, the amount of the encapsulant filling in the package is as important as a ratio of mixing the silicon resin and the yellow phosphor. The encapsulant is supplied using a dispensing device. When the encapsulant is supplied, the bucket may not be coated with the encapsulant since the encapsulant is not properly supplied, or may overflow due to the excessive supply of the encapsulant. The ingress of foreign substances or damage to the bucket may also occur in the process of supplying the encapsulant. Since these defects cause a deterioration of the white LED, a test to determine whether the white LED is acceptable or defective is necessary in the manufacturing process.
However, the test to determine whether a white LED is acceptable or defective is being performed with the naked eye.
As for the test with the unaided eye, objective test criteria is ambiguous among inspectors, and the reliability of test results is reduced due to the difference in detection ability between skilled and unskilled inspectors.